To provide improved performance and cost-effectiveness of multilayer integrated circuits in the electronic field, a recent trend is to increase the density of the multilayer integrated circuits, for example increase the number of memories and logic chips. For this, a chip size has decreased. At the same time, a significant effort has been made in developing a new dielectric material that can decrease the dielectric constant of a dielectric film. A low dielectric film material recently used is silicon dioxide with a dielectric constant of about 3.5 to 4.0. The silicon dioxide has a physical strength and thermal stability sufficient to withstand various chemical or thermal processes related to a semiconductor fabrication method.
However, recent high performance multilayer integrated circuits require a relatively inexpensive copper conductor with excellent conductivity and a new low dielectric material that can satisfy a dielectric constant of 2.5 or less. Signal retardation and cross-talk phenomena accompanied by a decrease in the size of an integrated circuit act as serious blocking factors against device performance improvement. To solve such signal retardation and cross-talk problems, studies about a low dielectric material have been actively done. Development of an ultra-low dielectric material requires introduction of nanoscale pores into a dielectric material or film. For this, a thermal decomposition of an organic polymer that can form nanoscale pores is mainly used. However, a recent technology is difficult to control the size and distribution of nanoscale pores to an ideal level. This is because there arise a phase separation phenomenon between a dielectric material and a pore-forming polymer, and thus, the problem of lack of uniformity of the size and distribution of pores.
Recently, there have been done many studies to develop low dielectric materials based on silicate- and nanoporous silicate- polymers, aromatic polymers, fluorinated aromatic polymers, organic/inorganic composite materials, and the like. In addition to a dielectric constant of 2.5 or less, development of ultra-low dielectric materials also requires improvements of characteristics necessary for a semiconductor device fabrication process and the durability of semiconductor devices, such as thermal stability, mechanical properties, chem.-mech polishing compatibility, etching property, interface compatibility, and electrical properties.